The investigation is set to focus on a number of factors, including the type of substances allegedly used, waiver documents players were supposedly asked to sign and the Bombers' high injury toll during the 2012 season.

More than half of the club's playing list suffered some kind of soft tissue injury last season, predominately hamstring related.

It is believed 'peptides' – the type of substance reportedly used – have an ability to promote muscle growth, but soft tissue injuries can be a symptom.

After morning meetings at AFL House on Tuesday, Essendon chairman David Evans told an afternoon press conference that the Bombers had received information in the preceding 48 hours raising concerns about the supplements.

Evans said the Bombers had contacted the AFL and ASADA to launch an immediate joint investigation.

"Of course this is a very distressing time for our club, our executive, our players and our board. We believe as a club that we have done everything right to be compliant with the rules and regulations of the AFL and ASADA," he said.

"But the integrity of the club is critical to the people sitting at this table and, of course, for the broader Essendon family. And that is why we have moved quickly today to call the AFL and ASADA to seek a clean bill of health.

"The info we gathered over the last 24 or 48 hours is slightly concerning, and we want to dig a bit deeper but we want the AFL to help us."

Evans was accompanied at the press conference by Essendon CEO Ian Robson and coach James Hird.

"I'm very disappointed, shocked is probably the best word," Hird said.

"As a coach I take full responsibility for what happens in our footy department.

"If there have been goings on within our football department that are not right we want to know.

"But it's my belief, though, that we have done everything right and that … the supplements that our players were given … were all approved and within the regulations that we all play the games by."

Evans refused to directly answer questions on the nature of the information Essendon had received about the supplements, where that information had come from, and whether it raised concerns about performance-enhancing drugs.